h1{
    color:yellowgreen;
    text-align:center;
    font-style: italic;
}
h2{
    color:green;
    text-decoration:underline;
}

#h1-1{
    font-size:50px;
}

.xietie{
    font-style: italic;
}

.youbiankuang{
    border:10px solid green;
}